The depth of a keyway is an important part quality characteristic. Samples of size n = 5 are ta ken every four hours from the process and 20 samples are summarized as follows: Sample 3 r 1 139.7 1.1 2 139.8 1.4 3 140.0 1.3 4 140.1 1.6 5 139.8 0.9 6 139.9 1.0 7 139.7 1.4 8 140.2 1.2 9 139.3 1.1 10 140.7 1.0 11 138.4 0.8 12 138.5 0.9 13 137.9 1.2 14 138.5 1.1 15 140.8 1.0 16 140.5 1.3 17 139.4 1.4 18 139.9 1.0 19 137.5 1.5 20 139.2 1.3 (a) Using all the data find trial control limits for X and R charts. Use the coded units. Round your answers to 1 decimal place (e.g. 98.7). X Control Limits: UCL = i CL : LCL = i R Control Limits: UCL = CL = i LCL = i (b) Construct X and R control charts using the control limits from part (a) to identify out-of-control points. (Use Minitab, Excel or any other statistical software.) The process appears to be